In a communication system, a PN sequence with known characteristics can be transmitted to the receiver for performing synchronization or channel estimation using the PN sequence. The general methods include calculating the linear correlation or circular correlation between the received signal and the PN sequence for performing synchronization or channel estimation. FIG. 1A shows a schematic diagram of performing linear correlation according to the prior art. FIG. 1B shows a schematic diagram of performing circular correlation according to the prior art. The linear or circular correlation multiplies and accumulates the corresponding bits of the received signal y(n) and the PN sequence p(n). Thereby, if the length of the input sequence y(n) is long, the adder and the amount of the adding operations in the receiver are increased, complicating and increasing the cost of the receiver. In addition, when the receiver computes correlation between the input sequence y(n) and the PN sequence p(n), the input sequence stored in the memory has to be accessed continuously. As a result, the operational speed is lowered, and hence the operational efficiency is reduced.
Accordingly, the present invention provides a method for computing correlation of a PN sequence and a circuit thereof, which can reduce the amount of operations and the number of times by which the memory is accessed.